Terpenoid means 50,000 or more natural compounds which has an isoprene unit with 5 carbon atoms as a basic skeleton. Terpenoid can be classified into hemiterpenes (C5), monoterpenes (C10), sesquiterpenes (C15), diterpenes (C20), sesquiterpenes (C25), triterpenes (C30), tetraterpenes (C40), and other polyterpenes, according to the number of carbon atoms thereof. In a biosynthesis thereof, various prenyl diphosphate having varying numbers of carbon atoms are prepared by condensation polymerization of isopentenylpyrophosphate (IPP) and dimethylallyl diphosphate (DMAPP) which is prepared by isomerization of isopentenyl diphosphate. Monoterpenes (C10) are biologically synthesized from geranyl diphosphate having 10 carbon atoms, sesterterpenes (C15) are biologically synthesized from farnesyl diphosphate having 15 carbon atoms, and diterpene and the like are biologically synthesized from geranylgeranyl diphosphate having 20 carbon atoms.
For a long time, it has been believed that IPP and DMAPP, which are necessary for the biosynthesis of terpenoid, are biologically synthesized only in the “mevalonate pathway” wherein the mevalonic acid is used. However, it becomes apparent that IPP and DMAPP are biologically synthesized through the methylerythritol phosphate (MEP) pathway, which is present in many eubacteria or plastid of plants (non-patent literature 1), in addition to the “mevalonate pathway”.
As the terpenoid, in addition to unsaturated hydrocarbons of (C5H8)n, redox products thereof (alcohol, ketone, acid, etc.), compounds in which carbon(s) are removed, or the like, are found in bodies of many plants and animals, and many having a physiological activity are comprised therein. For example, the above terpenoids comprise compounds which have a key role in a living body, i.e., phytohormone such as abscisic acid, gibberellin, brassinosteroid, or juvenile hormone; or complex terpenes which have an isoprene structure as a part of the structure, such as chlorophyll, vitamin K, ubiquinone, and tRNA, which exhibit a useful physiological activity. Vitamin K is an important vitamin involved in a blood coagulation system, and is used as a hemostat. Recently, an involvement of vitamin K in bone metabolism is suggested, and thus it is expected that vitamin K is applied to a treatment of osteoporosis. Further, phylloquinone and menaquinone are approved as a medicine. Furthermore, ubiquinone and vitamin K(s) exhibit an inhibitory effect on adhesion of shellfish to a body of a ship or construction such as a bridge pier, and therefore it is expected that they are applied to paint for inhibiting adhesion of shellfish. Further, carotenoids exhibit antioxidant action, and thus it is expected that β-carotene, astaxanthin, cryptoxanthin, and the like, are effective in preventing cancer, or exhibits immunostimulatory activity.